1. Field of the Invention
This invention relates to a method of increasing the flow of hydrocarbon liquids through conduits. More particularly, it relates to a method of increasing the flow rate of hydrocarbon liquids such as crude oil in conduits such a pipelines by reducing the frictional resistance of the hydrocarbon liquid flowing in the conduit.
2. Prior Art
When fluids are pumped through a conduit, such as a pipeline, friction resulting from the movement of the fluid over the inside surface of the conduit causes a pressure drop in the fluid which increases as the downstream distance from the pump increases. Because of the loss in pressure, it is usually necessary to install additional pumps at selected points along the pipeline to keep the fluid moving at the desired rate in the conduit. Sometimes it is desirable to increase the throughput of fluids through conduits but this cannot always be satisfactorily accomplished by installing additional booster pumps. The flow rate of the fluid through the conduit can also be increased by reducing the friction of the fluid in the conduit. Accordingly, it would be desirable to find an efficient technique for reducing the pressure loss due to friction, commonly referred to as "friction loss" or "drag."
One method of reducing friction loss in fluids moving through conduits is to inject into the fluid a substance which is capable of reducing the friction loss of the fluid moving through the conduit. Such substances must not only reduce the friction loss of the fluid, but must be compatible with the fluid and must not interfere with the intended use of the fluid.
Recent shortages in imported crude oil have made it necesssary to increase the flow of crude oil moving through existing pipelines from domestic oil fields to refineries. Studies have been undertaken to find substances which meet the requirements stated above. It has been discovered that certain oil-compatible polymeric substances have been used with some success in reducing friction loss in crude oil through pipelines. U.S. Pat. No. 3,692,676 discloses the reduction of friction loss in hydrocarbon liquids flowing through pipelines by adding to such liquids small amounts of homopolymers or copolymers of alpha-olefins having from 6 to 20 carbon atoms. Even though such additives may effect drag reduction in hydrocarbon liquids flowing through conduits they are costly to use since the described polymers are prepared from monomers which are expensive and not readily available in large quantities.
Oil-compatible drag reducing agents have been prepared from less costly monomers but these generally have not been completely satisfactory, often for such reasons as their inability to sufficiently reduce the friction loss of the flowing liquid or their propensity to undergo excessive shear degradation under actual field conditions. In this category are drag reducing agents disclosed in U.S. Pat. No. 3,215,154, which teaches the use of polyisobutylene as a hydrocarbon liquid friction loss reducing agent; U.S. Pat. No. 3,434,485, which discloses the use of low molecular weight polybutene to reduce friction loss in a crude oil pipeline; U.S. Pat. Nos. 3,351,079; 3,493,000; 3,559,664 and 3,682,187, which disclose the addition of copolymers of ethylene and propylene or other low molecular weight alpha-monoolefin to to hydrocarbon fluids as fluid flow friction loss reducing additives; and U.S. Pat. No. 3,454,379, which describes the addition of low molecular weight polyethylene to distillate hydrocarbon fuel oil to improve the pumpability of the fuel oil.
An efficient method of reducing the friction loss of hydrocarbon liquids flowing in conduits using inexpensive chemical additives which do not undergo significant shear degradation has now been discovered. Accordingly, it is an object of the invention to present an improved method of reducing friction loss in hydrocarbon fluids flowing through conduits. It is another object of the invention to present an inexpensive and efficient method of reducing friction loss in hydrocarbon fluids flowing through conduits. It is another object of the invention to present novel polymeric compositions having unexpected hydrocarbon pipeline friction reducing properties. It is another object of the invention to present a method of reducing friction loss in a hydrocarbon fluid flowing through a conduit by means of a polymeric additive which does not undergo significant shear degradation under actual field conditions. It is another object of the invention to present an inexpensive and efficient method of reducing the friction loss in crude oil flowing through pipelines. These and other objects of the invention are supported in the following description and examples.